Rolling for rarity against legal items?

By Desslok, in Star Wars: Edge of the Empire RPG

Okay, perhaps I'm just not seeing it listed in the book, but what does one roll against the rarity for legal items? I know it's streetwise if your looking for blasters or whatnot - per page 150 - but if someone is looking for some completely legal armor or something? What - just straight Negotiation?

It is negotiation.